energy drinks ui

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Energy Drinks: An Assessment of Their Market Size, Consumer Demographics, Ingredient Profile, Functionality, and Regulations in the United States M.A. Heckman, K. Sherry, and E. Gonzalez de Mejia ABSTRACT: The consumption of energy drinks is rapidly increasing, as demonstrated by their large market growth. The targeted demographic group is teenagers, young adults, 18 to 34 y old; although expansion into nontraditional markets is also occurring. It is claimed that energy drinks can offer an increased energy boost related to their ingre- dient profile of caffeine, taurine, herbal extracts, and vitamins. Research suggests that energy drink formulations, in addition to increasing energy utilization, may also improve mood, enhance physical endurance, reduce mental fatigue, and increase reaction time. However, in most cases, the corresponding mechanisms of action are not clear. In addition, concerns have been raised over their safety and with a currently weak regulatory environment, efforts need to be made to ensure consumer safety. The objective of this article is to review the current U.S. energy drink market with emphasis on its market size, target demographic, active ingredients, potential benefits, safety, and reg- ulations. Introduction Energy drinks refer to beverages that contain, besides calories, caffeine in combination with other presumed energy-enhancing ingredients such as taurine, herbal extracts, and B vitamins. They first appeared in Europe and Asia in the 1960s in response to consumer demand for a dietary supplement that would result in increased energy (Reissig and others 2009). In 1962, a Japanese company, Taisho Pharmaceuticals, launched Lipovitan D, one of the very 1st energy drinks, which is still dominating the Japanese market. Lipovitan D contains B vitamins, taurine, and ginseng, which are all frequent constituents of mainstream energy drinks with the intended purpose of providing the consumer with sus- tained energy, and to reduce mental and physical fatigue (Taisho Pharmaceutical Co. Ltd. 2009). Energy drinks did not make their MS 20091110 Submitted 11/5/2009, Accepted 1/15/2010. Authors are with Dept. of Food Science and Human Nutrition, Univ. of Illinois Urbana- Champaign, IL 61801, U.S.A. Direct inquiries to author de Mejia (E-mail: [email protected] ). way into the U.S. market until 1997 when Red Bull was first intro- duced, which originated and was initially launched 10 y earlier in Austria (Reissig and others 2009). Since the 1960s, the en- ergy drink market has grown into a multibillion dollar business which has been reported as being the fastest growing segment in the beverage industry since bottled water (Agriculture and Agri- Food Canada 2008). Energy drinks have established a viable posi- tion in the beverage market as evidenced by their commonplace consumption in the morning, afternoon, and night, not only by the general consumer, but those of age 18 to 34 in particular (Lal 2007). Importance should be placed on consumer safety and the understanding on how these beverages are regulated. The ob- jective of this review is to give a general overview of the current energy drink market in regard to its size, target market, ingredient profile, potential benefits, safety, and regulations. Market Size Energy drinks fall into the category of functional beverages, which also encompasses sports and nutraceutical drinks as c 2010 Institute of Food Technologists R Vol. 9, 2010COMPREHENSIVE REVIEWS IN FOOD SCIENCE AND FOOD SAFETY 303

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Page 1: Energy drinks ui

Energy Drinks: AnAssessment of

Their Market Size,Consumer

Demographics,Ingredient Profile,Functionality, andRegulations in the

United StatesM.A. Heckman, K. Sherry, and E. Gonzalez de Mejia

ABSTRACT: The consumption of energy drinks is rapidly increasing, as demonstrated by their large market growth.The targeted demographic group is teenagers, young adults, 18 to 34 y old; although expansion into nontraditionalmarkets is also occurring. It is claimed that energy drinks can offer an increased energy boost related to their ingre-dient profile of caffeine, taurine, herbal extracts, and vitamins. Research suggests that energy drink formulations,in addition to increasing energy utilization, may also improve mood, enhance physical endurance, reduce mentalfatigue, and increase reaction time. However, in most cases, the corresponding mechanisms of action are not clear.In addition, concerns have been raised over their safety and with a currently weak regulatory environment, effortsneed to be made to ensure consumer safety. The objective of this article is to review the current U.S. energy drinkmarket with emphasis on its market size, target demographic, active ingredients, potential benefits, safety, and reg-ulations.

IntroductionEnergy drinks refer to beverages that contain, besides calories,

caffeine in combination with other presumed energy-enhancingingredients such as taurine, herbal extracts, and B vitamins. Theyfirst appeared in Europe and Asia in the 1960s in response toconsumer demand for a dietary supplement that would result inincreased energy (Reissig and others 2009). In 1962, a Japanesecompany, Taisho Pharmaceuticals, launched Lipovitan D, one ofthe very 1st energy drinks, which is still dominating the Japanesemarket. Lipovitan D contains B vitamins, taurine, and ginseng,which are all frequent constituents of mainstream energy drinkswith the intended purpose of providing the consumer with sus-tained energy, and to reduce mental and physical fatigue (TaishoPharmaceutical Co. Ltd. 2009). Energy drinks did not make their

MS 20091110 Submitted 11/5/2009, Accepted 1/15/2010. Authors are withDept. of Food Science and Human Nutrition, Univ. of Illinois Urbana-Champaign, IL 61801, U.S.A. Direct inquiries to author de Mejia (E-mail:[email protected]).

way into the U.S. market until 1997 when Red Bull was first intro-duced, which originated and was initially launched 10 y earlierin Austria (Reissig and others 2009). Since the 1960s, the en-ergy drink market has grown into a multibillion dollar businesswhich has been reported as being the fastest growing segment inthe beverage industry since bottled water (Agriculture and Agri-Food Canada 2008). Energy drinks have established a viable posi-tion in the beverage market as evidenced by their commonplaceconsumption in the morning, afternoon, and night, not only bythe general consumer, but those of age 18 to 34 in particular (Lal2007). Importance should be placed on consumer safety and theunderstanding on how these beverages are regulated. The ob-jective of this review is to give a general overview of the currentenergy drink market in regard to its size, target market, ingredientprofile, potential benefits, safety, and regulations.

Market SizeEnergy drinks fall into the category of functional beverages,

which also encompasses sports and nutraceutical drinks as

c© 2010 Institute of Food Technologists R© Vol. 9, 2010—COMPREHENSIVE REVIEWS IN FOOD SCIENCE AND FOOD SAFETY 303

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CRFSFS: Comprehensive Reviews in Food Science and Food Safety

Figure 1 --- The market share breakdown of the functionalbeverage category in the U.S. (Datamonitor 2008a).

depicted in Figure 1 (Datamonitor 2008a). Sports drinks are de-signed to be consumed before or during exercise to prevent de-hydration, supply carbohydrates, provide electrolytes and typ-ically do not contain caffeine (Coombes and Hamilton 2000).Nutraceutical beverages, on the other hand, are designed topromote and enhance health, usually containing bioactive com-pounds such as concentrated extracts from teas, fruits, and veg-etables or herbs. Additionally, some nutraceutical beverages arefound to be fortified with vitamins and minerals and contain sig-nificant levels of antioxidants, particularly polyphenols. In someinstances, energy drinks could overlay into the nutraceutical bev-erage category depending on their ingredient composition. Theenergy drink segment encompasses an array of options includ-ing ready-to-drink (RTD), shots, and in powder form. Globally,energy drinks hold 47.3% of the functional beverage’s overallmarket share, while in the United States they comprise 62.6%(Datamonitor 2008a, 2008b). Energy drinks in particular haveexperienced impressive growth of more than 240% in the UnitedStates, as well as abroad, from 2004 to 2009 (Mintel 2009). In2008, the functional beverage industry reached global sales of$26.9 billion with a compound annual growth rate (CAGR) of8.6% from 2004–2008. The United States contributed signifi-cantly to the functional beverage industry’s total accounting for$7.6 billion in revenue and a CAGR of 20.6%. In addition, theU.S. energy drink industry is anticipated to more than doubleand reach an astounding $19.7 billion in 2013, which is almosta 160% increase from 2008 (Datamonitor 2008a). Within thefunctional beverage category, the energy drink segment has ex-perienced the largest volume growth and increased annual sales,both in the United States and abroad, reaching $4.8 billion in2008 in the United States alone (Datamonitor 2008a). This isa higher market value than that reported in the same year forsports drinks ($2.0 billion) and nutraceutical drinks ($0.08 bil-lion). Table 1 depicts volume growth and expected future growthof the functional beverage category. The numbers indicate thatenergy drinks will see their strongest growth between the years2007 and 2012 (GMID 2008). This increased growth can be at-tributed to more private label initiatives, larger container sizes,multi-pack options, sugar-free versions, and juice hybrids thathave a more palatable flavor (GMID 2008; Canadean 2009).Currently, there are more than 300 varieties of energy drinks

Table 1 --- U.S. functional beverage market volume growth(%) and growth forecast, 2007–2012.

2006/07 2002– 2007–volume 2007 2002/07 2012 2007/12

Category growth (%) CAGR total CAGR total

Sport drinks 1.5 11.3 70.7 0.2 0.8Energy drinks 32.0 45.8 558.7 9.9 60.2Nutraceutical 5.1 13.6 89.1 1.9 9.8

drinks

CAGR = compound annual growth rate.

Table 2 --- Market share of mainstream energy drinks inthe U.S. market.

Brand Company Market share (%)

Amp PepsiCo 3.6Full Throttle Coca-Cola Co. 6.9Rockstar Rockstar Inc. 11.4Monster Monster Beverage Co. 14.4Red Bull Red Bull Inc. 42.6

representing more than 200 brands in the United States alone,all purporting to increase energy, longevity, and vitality in someform or another (Energyfiend 2009). Although there is an abun-dance of energy drinks to choose from, Table 2 shows that themajority of the market share comprises only a handful of va-rieties, with Red Bull accounting for 42% of the market share(Beverage Spectrum 2008). According to a report by Agricultureand Agri-Food Canada (2008), 1.5 billion cans of Red Bull weresold in the United States in 2004, highlighting the enormity ofthis industry. The remaining 20% of the market share that is notaccounted for in Table 2 represents energy drink brands that cor-respond to less than 3.6% of the market share. In sum, the energydrink industry has proven extremely profitable and is anticipatedto continue with this same success in the years to come withnew and innovative product launches reaching a more expandedmarket.

Target PopulationAthletes initially were the primary consumers of energy drinks.

However, as the energy drink market grew and expanded intovarious niche markets, athletes are no longer the primary target.Today, the majority of energy drinks are targeted at teenagers andyoung adults 18 to 34 y old due to this generation’s on-the-golifestyle and receptiveness to advertisements for these types ofproducts (Lal 2007).

The popularity of energy drinks among the younger generationis evidenced by 34% of 18 to 24-y-olds being regular energy drinkusers (O’Brien and others 2008; Mintel 2009). Another reportfound that about one-half of college students consume at least 1energy drink per month in the hope to increase their energy level,to compensate for a lack of sleep or to mix with alcohol (Miller2008). The marketing and branding of many energy drinks reflectsthe market to which these companies are targeting. A reviewpresented at the 2007 IFE (Intl. Franchise Expo) Americas Foodand Beverage Show confirmed that energy drink companies’ pri-mary target market was adolescents and young adults (Agriculture

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Energy drinks . . .

and Agri-Food Canada 2008). Their appraisal stated that many ofthe energy drink companies were using cross-promotional tac-tics to reach their consumer base by integrating their productwith extreme sporting events, such as the X-games or NASCAR,as well as advertising their products in connection with pop-ular music icons (Agriculture and Agri-Food Canada 2008). Inaddition to those tactics, energy drink companies are using cre-ative, and in some cases intentionally defiant names for theirproducts to draw in consumers, some examples being Full Throt-tle, Ammo, Havoc, Hydrive, and Morning Spark (Energyfiend2009).

The target market for energy drinks is broadening as new prod-ucts are developed in an effort to reach niche submarkets anddifferentiate themselves from their competition. Such submar-kets include energy drinks just for woman, the carbohydrate-conscious, body-builders, or extreme sports enthusiasts. In 2007,Del Monte Foods launched its 1st energy drink called Bloom En-ergy claiming that it was formulated specifically with women inmind. Other energy drinks are targeted toward athletes such asLucozade Sport and Revenge Sport which play up their adver-tised ability to increase physical performance and reduce fatiguein high-endurance sports. The developers of Energy Fizz reachedconsumers through a different marketing approach, promotingthe convenience of being a powder that is packaged in a smallportable tube that can be easily added to water on the go to getthat needed energy boost. Although the use of on-the-go drinkmixes is not a new concept for the beverage industry as a whole,it is within the energy drink category.

Other energy drinks promote the unique qualities that makethem stand out from the rest, such as being all natural, organic,or gluten-free, as well as diabetic- or vegetarian-friendly. Energydrinks are still a developing industry in which a diverse range ofnew and innovative products will be seen in the years to come,with new innovations geared more toward the increasing numberof health-conscious individuals.

Behavioral Impact of Energy Drink ConsumptionThere have been conflicting results concerning the effect of

energy drinks on physiological and cognitive performance. Somestudies reported no significant differences in either the physiolog-ical or cognitive performance of individuals who have and havenot consumed energy drinks (Umana-Alvarado and Moncada-Jimenez 2004; Carvajal-Sancho and Moncada-Jimenez 2005).Research has aimed at determining the behavioral effects thatenergy drinks have on consumers, specifically, on their mood,concentration, reaction time, alertness, endurance, physical per-formance, and risk taking. The cognitive and physiological ef-fects after the consumption of an energy drink in comparison to aplacebo resulted in significantly improved performance on bothsecondary memory and speed of attention (Scholey and Kennedy2004).

Another study looked at the effect of Red Bull on cognitiveperformance and well-being of the studied subjects, concludingthat its consumption had a positive impact, possibly related tothe combination of caffeine, taurine, glucuronolactone, and B-vitamins present in the product, rather than just to a single ingre-dient (Seidl and others 2000; Alford and others 2001). Comparingthe consumption of energy drinks to a placebo also revealed thatenergy drinks had an energizing effect with the strongest effect be-tween 30 to 60 min after consumption with the individuals havingsustained energy up to 90 min (Smit and others 2004). The con-sumption of Red Bull also proved to be beneficial in improvingaerobic endurance and anaerobic performance, which supported

a previous study where there was a significant increase in over-all physical endurance of trained athletes after the consumptionof 250 mL of the product (Geiss and others 1994; Alford andothers 2001). Another study showed that consuming 500 mL ofa commercial energy drink (2.0 g taurine, 1.2 g glucuronolac-tone, 160 mg caffeine, 54 g carbohydrate, 40 mg niacin, 10 mgpantothenic acid, 10 mg vitamin B6, and 10 μg vitamin B12)before exercise, endurance, and physical performance can beimproved in comparison to a flavored placebo (Ivy and others2009). Improvements in visual information processing, attention,and verbal reasoning have also resulted from the consumptionof energy drinks (Warburton and others 2001). Furthermore, astudy looked at the effect of an energy blend containing caffeine(80 mg), taurine (1 g), glucuronolactone (6 mg), vitamins (50 mginositol and vitamin B complex per 250 mL), and sugar (21 gsucrose and 5 g glucose) on counteracting driver sleepiness andconcluded that this blend was beneficial in reducing sleepinessand sleep-related driving incidents (Reyner and Horne 2002).There have also been several studies that have looked at the asso-ciation between energy drink consumption and problem behav-ior. The results of a recent study concluded that increased energydrink consumption was associated with increased risk-taking be-haviors (Miller 2008).

The psychological and performance-enhancing effects of caf-feine have been reported after large dosages that are unachievablein everyday circumstances, as well as after consumption of real-istic doses (Scholey and Kennedy 2004). Research has shown thata modest consumption of 12.5 to 100 mg of caffeine can improvecognitive performance and mood (Smit and Rogers 2000). Dosesof caffeine of 6 mg/kg body weight (BW) and 9 mg/kg BW wereequally as effective in increasing exercise performance, conclud-ing that larger doses of caffeine may not deliver a better response(Bruce and others 2000). Another study found that ingesting asports drink containing caffeine at a level of 2.1 mg/kg BW hadan ergogenic effect on exercise performance; however, doses of3.2 and 4.5 mg/kg BW had a greater effect (Kovacs and others1998). Based on the literature, it appears that a dose of caffeineof 3 to 6 mg/kg BW would be adequate for this purpose (Gra-ham 2001). Davis and Green (2009) indicated that a definiteconclusion cannot be reached on the extent caffeine affects per-formance and that the exact mechanism of caffeine remains tobe elucidated.

On the other hand, an association between consumption ofenergy drinks and occurrence of cardiovascular events has re-cently been questioned, although the supporting data are limited.Regardless of the evidence, this association has brought aboutconcerns that have impacted consumer perception and have re-sulted in bans on the sale of energy drinks in several Europeancountries including Denmark and Norway (Ragsdale and others2009). To further investigate this phenomenon, a double-blindstudy was conducted comparing the electrocardiograms of 68college-aged students before and after consumption of 250 mLRed Bull, concluding that there was no difference between anyof the measured cardiovascular parameters (Ragsdale and others2009). Also the consumption of 2 servings of 480 mL of MonsterEnergy drink found the same lack of changes in cardiovascu-lar function (Dentzer and others 2009). In another study, young,healthy adults consuming 500 mL of a commercially availableenergy drink experienced no significant changes in their elec-trocardiograms in comparison to a placebo group; however, aminimal increase in heart rate and systolic blood pressure wasobserved (Steinke and others 2009).

Another common practice, especially among college students,is to mix alcohol with energy drinks (O’Brien and others 2008).It was found that almost 25% of all drinker college students mix

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Figure 2 --- Chemical structures ofactive ingredients commonly found inenergy drinks. A. Major componentsof guarana: (a) caffeine, (b)theobromine and, (c) theophylline.B. B-vitamins (Helmenstine 2009).C. Taurine.

alcohol with energy drinks (O’Brien and others 2008). The con-cept of alcoholic energy drinks has been a very controversial issuein which the alcohol industry has received much criticism dueto the dangers that have been associated with this trend. Therehave been several studies that have shown that the consumptionof energy drinks in combination with alcohol have resulted ina decreased level of perceived intoxication, which could resultin an increased number of driving accidents or other alcohol-related incidents (Ferreira and others 2006; Marczinski and Fill-more 2006). The masking effect that energy drinks are proposedto have over alcohol intoxication is due to the combination of thestimulatory effect of caffeine and the depressant effect of alcoholon the body, hindering the true awareness of the typical signs ofalcohol intoxication such as drowsiness (Oteri and others 2007).However, one study found no significant differences amongsubjects who consumed alcohol in combination with energydrinks and those who just consumed alcohol (Ferreira and others2004).

Further research is needed to better understand this associa-tion as well as increased awareness of the potential dangers thatcould result from the combination of alcohol and caffeinatedbeverages.

Active IngredientsAlthough there are hundreds of energy drinks in the market,

many share very similar ingredient profiles. Most of these uniqueenergy blends consist mainly of caffeine and taurine at varyingconcentrations. In addition, sugar is typically added; however,many brands have sugar-free options available as well. Sugaris widely used in energy drinks because it is a source of rapidenergy. Other ingredients that are commonly incorporated intothese products are ginseng, guarana, yerba mate, and green teaextracts. Figure 2 and 3 show the chemical structures of the morefrequently used active ingredients in energy drinks. The variousingredient combinations are critical because those give a bever-age its distinct overall flavor, the amount of energy, as well asthe duration at which that energy will last, and lastly the claimedhealth properties of the beverage. Table 3 is a compilation of thepopular energy-enhanced beverages that are currently sold andtheir ingredient breakdown.

CaffeineThe majority of energy drinks contain caffeine as an active

ingredient due to its stimulatory effect on the central nervous

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Energy drinks . . .

Figure 3 --- Selected ginsenosides isolated from Panax gin-seng (Kim and others 2007).

system. Figure 4 shows a comparison of the caffeine concen-tration of several mainstream commercial energy drinks withbrewed coffee, yerba mate, and green tea. Additionally, Table 3gives the ingredient list of a variety of energy-enhanced beveragesindicating the presence of caffeine.

The main mechanism of action of caffeine, in concentrationstypically achieved after the consumption of a caffeinated bev-erage, is to act as an adenosine receptor blocker in the brain(Dunwiddie and Mansino 2001; Pettenuzzo and others 2008).Caffeine has a similar chemical structure to that of adenosine al-lowing caffeine to attach to the adenosine receptors. The block-age of adenosine to the neurons causes the sleep promotingeffects of adenosine to stop, resulting in the neurons speedingup instead of slowing down (Ferre 2008). Caffeine is also knownto increase the secretion of epinephrine, which can lead to avariety of secondary metabolic changes that can positively affectphysical or mental performance (Graham 2001). Once ingested,caffeine is rapidly absorbed from the gastrointestinal tract andundergoes demethylations which result in paraxanthine (84%),theobromine (12%), and theophylline (4%); with the xanthenestheobromine and theophylline having very similar chemicalstructures compared to caffeine (Safranow and Machoy 2005)(Figure 5). Caffeine has been widely studied in a variety ofareas regarding human health and performance and it is evi-

dent that caffeine consumption can increase energy utilization(Smit and Rogers 2002). Many studies also confirm its abilityto enhance mood and alertness (Kaplan and others 1997; Smitand Rogers 2002; Lorist and Tops 2003), exercise performance(Graham 2001; Doherty and Smith 2004), the speed at which in-formation is processed, awareness, attention, and reaction time(Cysneiros and others 2007). Caffeine has also been shown to re-duce some of the negative side effects associated with sleep loss.Some studies suggest that caffeine can contribute to improvedalertness and performance at doses of 75 to 150 mg after acutesleep loss and doses of 200 to 600 mg after a night or morewithout sleep (Bonnet and others 2005).

Caffeine also has a stimulatory effect on thermogenesis (Ache-son and others 1980; Dulloo and others 1989; Astrup and others1990; Bracco and others 1995). In addition, caffeine consump-tion has also been linked to reduced food intake (Tremblay andothers 1988; Racotta and others 1994; Lima and others 2005)and to promote lipolysis in both animals and humans (Hasegawaand Mori 2000; Zheng and others 2004; Kobayashi-Hattori andothers 2005; Lopez-Garcia and others 2006).

A review regarding caffeine consumption concluded thatamong the healthy adult population, a moderate daily caffeineintake of ≤400 mg (equivalent to 6 mg/kg/d for a 65 kg person)was not associated with any adverse effects (Nawrot and others2003). Figure 4 shows a comparison of the amount of caffeinefound in commonly consumed beverages. The average caffeinecontent of an energy drink typically ranges from 80 to 140 mg/8oz, well below this ≤400 mg per day limit and is comparableto consuming 5 ounces of coffee or 2 cans of a caffeinated softdrink (Malinauskas and others 2007). However, it is important tobe aware of the serving size since many of the 16-oz contain-ers hold 2 servings. Caffeine also has a diuretic effect regardlessof its consumption as energy drink, tea, or coffee (Riesenhu-ber and others 2006). There are, however, several studies thatconclude that caffeine consumption at physiologically relevantdosages does not cause diuresis (Falk and others 1990; Scott andothers 2004; Armstrong and others 2007; Goldstein and others2010). Nonetheless, caution should be exercised in regard to theamount of caffeine consumed per day. Caffeine has a long his-tory of safe use and overwhelming scientific evidence maintainsthat when consumed in moderation (300 to 400 mg/d/adult) noadverse effects should occur.

TaurineTaurine (2-aminoethyl sulfonic acid) is a sulfur containing

amino acid that is the most abundant amino acid found naturallyin our bodies, primarily in the retina and skeletal and cardiacmuscle tissue (Timbrell and others 1995; Imagawa and others2009). Taurine is derived from the metabolism of methionine andcysteine (Huxtable 1992; Stipanuk 2004).

It is also present in common food items such as meat and fish.It has been estimated that the average daily human intake oftaurine is between 40 and 400 mg (Shao and Hathcock 2008).The incorporation of taurine into energy drinks and other prod-ucts has increased a great deal over the past 10 y with taurinealso being one of the most extensively used and studied aminoacids (Shao and Hathcock 2008). Energy drinks launched be-tween 2004 and 2008 were evaluated for the presence of taurine.The results showed that 1 in 4 (27%) energy drinks in 2004 con-tained taurine, whereas in 2008 it was reduced to 1 in 5 (21%)(Mintel 2009). This reduction could be due in part to a cost sav-ing initiative or the incorporation of alternative ingredients in theproduct formulation.

Taurine is associated with a variety of physiological func-tions including neuromodulation, cellular membrane stability,

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Figure 4 --- Caffeine (mg/8 oz)comparisons in a variety ofbeverages.

Figure 5 --- Metabolism of caffeine into its 3 metabolicdimethylxanthines.

and modulation of intracellular calcium levels, both, in vitro andin vivo (Huxtable 1992; Timbrell and others 1995; Brosnan andBrosnan 2006). However, further research is needed to better ex-plain the underlying mechanisms of action. Furthermore, taurinehas been seen to enhance endurance performance and to aid inthe reduction of lactic acid buildup after exercise (Matsuzaki andothers 2002; Imagawa and others 2009).

In the body, taurine undergoes mainly conjugation to form bilesalts as well as degradation to sulfate (Munro and Renwick 2006).This metabolism allows for larger dietary intakes of taurine, withexcess eliminated unchanged in the urine (Munro and Renwick2006).

Methods have been developed to discriminate between syn-thetic taurine and that derived from natural sources, suggestingan inferior nutritional value of the former (Gioacchini and others1995). However, more research is needed to conclude whether

there is a significant physiological difference between taurinefrom natural or synthetic sources.

The synthetic taurine that is present in energy drinks is found invery large concentrations. Taurine analysis of 80 different energydrinks showed an average concentration of 3180 mg/L which isequivalent to 753 mg/8 oz (Triebel and others 2007). Several stud-ies have been conducted aimed to determine the effect of taurineat various dosages ranging from 375 to 8000 mg/d, resulting inno adverse effects (Mantovani and de Vivo 1979; Kendler 1989;Ikeda 1977). Other studies have also looked into the safety of tau-rine in humans and found no adverse effects (Sirdah and others2002; Brons and others 2004; Zhang and others 2004). Althoughthere has been no evidence showing taurine to cause any adversehealth effects, concern has been raised since not enough researchhas been conducted on the effects of large quantities of taurine incombination with other ingredients commonly found in energydrinks.

GuaranaGuarana comes from the Paullinia cupana plant, indigenous to

South America. It originated in the Amazon basin in Brazil, whereit has had a long history of use (Angelo and others 2008). It iscommonly known for its small-berry like fruit it produces, whichcontains 1 to 3 dark seeds, which accounts for the only ediblepart of the guarana plant (Scholey and Haskell 2008). The seedscontain a significant amount of caffeine, with 1 g of guarana be-ing equivalent to about 40 mg caffeine (Finnegan 2003). Guaranacontains other xanthine alkaloids, specifically theobromine andtheophylline, however, at much lower levels compared to caf-feine (Weckerle and others 2003). In addition to the caffeine con-tent, guarana also contains relatively high amounts of saponins,flavonoids, and tannins, all contributing to its bioactive propertiesincluding its antioxidant activity (Espinola and others 1997; Mat-tei and others 1998). Guarana has become an increasingly com-mon natural additive in energy drinks in recent years largely for itsstimulatory effect (Scholey and Haskell 2008). It has been statedthat the caffeine from guarana is released at a slower rate com-pared to pure caffeine, giving off a more subtle and lengthier stim-ulatory effect (Scholey and Haskell 2008). It is purported that thisslower release is due to guarana being insoluble in water as wellas containing tannins and saponins (Edwards and others 2005).

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There is, however, no conclusive research that shows the caffeinerelease and absorption from guarana to be any different from thatof pure caffeine (Bempong and Houghton 1992). Guarana hasbeen suggested to improve cognitive performance, mental fa-tigue, and mood at physiologically relevant dosages; an effectsupported by several research studies (Haskell and others 2007;Kennedy and others 2008; Scholey and Haskell 2008). Guaranahas also been associated with inducing lipid metabolism, prob-ably due to its methylxanthine content (Lima and others 2005).Additionally, guarana has been shown to exert no toxic effectswhen consumed both in acute high dosages as well as in chroniclower dosages (Mattei and others 1998).

GinsengGinseng is a herb that has been used for over 2000 y by people

in East Asian countries including China, Japan, and Korea as aremedy for various diseases and for promoting longevity (Leeand others 2005; Nam and others 2005). Panax ginseng is theprimary commercial species and is often referred to as Korean orAsian ginseng. Siberian ginseng (Eleutherococcus senticosus) isnot truly a ginseng since it contains eleutherosides as its activeconstituent and no ginsenosides. P. ginseng is a small, shade-loving perennial shrub that reaches about 60 cm in height andbelongs to the plant family Araliacae. The entire ginseng planthas been used for medicinal purposes; however, the root is themost prominent and dominates the commercial sales. The rootsare typically not harvested until after the 5th or 6th year of growthwhen their ginsenoside concentrations are at their peak (Hu 1976;Mahady and others 2001). After harvest, P. ginseng can undergofurther processing, including drying and bleaching of the rootwith sulfur dioxide forming “white ginseng” or steaming the rootand air-drying it to form “red ginseng” (Hu 1976; Mahady andothers 2001).

The market for ginseng products and ginseng-related productshas been estimated at $3.5 billion worldwide and is forecast to in-crease as a result of the increased research on its pharmacologicaleffects (Hong and others 2006). There are several reported healthbenefits of ginseng which include being an immune stimulant,producing improved physical and mental conditions, and havingantistress, antiaging, antioxidant, and anti-inflammatory proper-ties (Coon and Ernst 2002; Lu and others 2009). These pharma-cological properties are attributed to its active constituents, withginsenosides being the most biologically active accounting for2% to 3% of ginseng (Okazaki and others 2006; Lu and others2009). Ginsenosides are secondary metabolites from the ginsengroot. They are triterpene saponins and more than 40 of these com-pounds have been isolated and identified (Nah and others 2007).Each ginsenoside has its own unique structure, therefore, variouspharmacological effects can result (Lu and others 2009). Manystudies have investigated a single purified ginsenoside rather thananalyzing a ginseng root extract in its entirety to determine andexplain the various mechanisms of action of ginseng (Zhouand others 2004; Cheng and others 2005; Hofseth and Wargovich2007). Ginsenosides have been found to inhibit ROS produc-tion, stimulate NO production, improve central nervous systemfunction, and prevent cardiovascular and other diseases (Lu andothers 2009). A systematic review and meta-analysis concludedthat there is insufficient evidence to have a conclusive statementon the effect of ginseng on physical performance, psychomotorperformance, and cognitive function (Vogler and others 1999).Interestingly, the same study concluded that ginseng may be ef-fective against diabetes mellitus and that more research is neededon this subject (Vogler and others 1999). However, another studyconcluded that there is conflicting evidence on the beneficialeffects of ginseng on blood glucose (Yeh and others 2003). A

randomized placebo-controlled clinical trial also assessed the ef-fects of P. ginseng extract G115, at a dose of 200 to 400 mg/d,on mood and other psychological parameters in young healthysubjects (Cardinal and Engels 2001). At the end of the study, noimprovements were observed in any measured parameter, indi-cating that ginseng has no beneficial effects on mood or memoryin young healthy subjects (Cardinal and Engels 2001). However,a different study reported improvements in mental fatigue afterthe administration of 200 mg P. ginseng G115 (Reay and oth-ers 2005). This study also concluded that 200 and 400 mg of P.ginseng G115 extract resulted in significant reductions in bloodglucose levels (Reay and others 2005). A recent review evaluatedthe potential beneficial effects of ginseng on hyperglycemia (Luoand Luo 2009). It was found that American ginseng increased in-sulin production and reduced death of pancreatic β-cells. Also,it decreased blood glucose in patients with type II diabetes aswell as in streptozotocin-induced diabetic animals (Luo and Luo2009). It was concluded that further research is needed to identifythe component(s) in ginseng which may be responsible for thesefavorable effects.

In view of the increasing popularity of ginseng and its reportedpharmacological effects, it is important to know whether or notthere are any health risks for the consumer. Based on severalstudies conducted with animals and humans, ginseng is “gener-ally considered safe” (Coon and Ernst 2002). However, the useof ginseng in very high doses has resulted in some side effects,which included hypertension, diarrhea, and sleep disturbances(Coon and Ernst 2002). Nevertheless, many other studies haveclaimed that, in comparison with other phytomedicines, ginsenghas not been shown to produce serious side effects or dangerousinteractions with other drugs (Nah and others 2007).

Yerba MateYerba mate comes from the Ilex paraguariensis plant which is

native to South America where its main function is for the produc-tion of yerba mate tea (Heck and de Mejia 2007). Yerba mate teais a commonly consumed beverage in South American countriesand has been for centuries; however, it is increasing in popu-larity globally due to its content of a variety of bioactive com-ponents including polyphenols, xanthines, flavonoids, saponins,amino acids, minerals, and vitamins (Heck and de Mejia 2007).The abundant array of phytochemicals present in yerba matehas been connected to various health benefits. Yerba mate pos-sesses anti-inflammatory and antidiabetic properties as well asacts as an inhibitor to oxidative stress (Heck and de Mejia 2007;Markowicz-Bastos and others 2007). Moreover, yerba mate hasshown in vitro cytotoxicity to cancer cells and inhibition againsttopoisomerase II, which plays a role in cell division and there-fore works to inhibit cancer cell proliferation (Heck and de Mejia2007); however, in vivo studies are needed. Yerba mate also hasa positive impact on the management of obesity, both in vivo andin vitro (Pang and Choi 2008; Arcari and others 2009; Martinsand others 2009). The consumption of yerba mate significantlyimproved the serum lipid parameters in normolipidemic and dys-lipidemic individuals (de Morais and others 2009). Furthermore,yerba mate enhanced the reduction in LDL-cholesterol levels inindividuals who were also under statin therapy (de Morais andothers 2009).

In addition, yerba mate is a central nervous system stimulantdue to its high caffeine concentration, which is the primary rea-son for yerba mate to be incorporated into energy drink formu-lations. The caffeine concentration in 1 cup (8 oz) of yerba matetea is equivalent to about 78 mg, which is very comparable to8 oz of Red Bull, which contains 80 mg (Heck and de Mejia2007).

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Figure 6 --- Diagram of thefluorescence degradation of anenergy drink in comparison to thecontrol buffer over time.

On the other hand, concerns have been raised regarding an as-sociation between yerba mate and the occurrence of certain typesof cancer, specifically oral, esophageal, lung, bladder, and renal(Heck and de Mejia 2007). However, there is no conclusive evi-dence that this association is a result of the consumption of yerbamate but rather due to various lifestyle choices including smok-ing and excessive alcohol consumption. In addition, these caseshave primarily been reported in certain areas of South Americawhere large amounts of yerba mate are consumed at very hot anddamaging temperatures which could lead to increased absorptionof carcinogens found in cigarette smoke or other environmentalpollutants (Heck and de Mejia 2007).

B VitaminsB vitamins are a group of 8 individual water-soluble vitamins,

usually referred to as the B complex when grouped together, andall play essential roles in cellular processes. B vitamins are in-corporated into many of the mainstream energy drinks. A typicalcan of 250 mL may contain 360% of the recommended dailyallowance (RDA) of B6, 120% of B12, and 120% of B3 (niacin).The container size varies among brands and it may hold multipleservings. The addition of excess amounts of B vitamins is alsoobserved in the more extreme energy drinks like 5-Hour Energywhich contains 8333% of the RDA for vitamin B12 and 2000%of the RDA for B6. It is claimed that the consumption of theselarge amounts of B vitamins increases mental alertness and fo-cus, as well as improves mood. The average person, however,consumes the RDA of B vitamins from a typical diet since B vi-tamins are found in a variety of foods including bananas, lentils,potatoes, tuna, and turkey. Vitamins B2 (riboflavin), B3 (niacin),B6 (pyridoxine, pyridoxal, pyridoxamine), and B12 are the mostcommon of the B vitamins that are incorporated into energy drinkformulations. Vitamin B2 is a coenzyme in the metabolism ofcarbohydrates. Vitamin B3 plays a major role as a coenzyme inenergy metabolism, fat synthesis, and fat breakdown (Wardlawand Smith 2009). Vitamin B6 is a group of 3 structurally similarcompounds that all can be converted into the vitamin B6 coen-zyme which aids in the utilization of carbohydrates, fats, andproteins (Wardlaw and Smith 2009). Vitamin B12 assists in folatemetabolism and in nerve function (Wardlaw and Smith 2009).Since all of the B vitamins are water soluble, once the RDA hasbeen met, the excess vitamins are excreted from the body via

urine. Although the consumption of a large amount of B vitaminsdoes not possess any adverse health effects, the logic behind theextreme amounts of B vitamins in these beverages is not wellrationalized.

Beverage Health FunctionalityIn addition to the energy-enhancing substances in energy

drinks, many also contain a variety of health-promoting con-stituents, including antioxidant polyphenols contributed by thevarious fruits or tea extracts added to the beverage formulations.Products high in antioxidants are important because they helpprotect the cells in the body from the damaging effects of free rad-icals known to damage proteins, lipids, and DNA, reducing therisk of diseases such as cancer and coronary heart disease (Awikaand others 2003; Miller and others 2006). Polyphenols containantioxidant properties and have been found to aid in the preven-tion of several degenerative diseases including cardiovasculardisease and cancer (Scalbert and others 2005). Several main-stream energy drinks, 16 nontea-based and 15 tea-based, wereanalyzed for their antioxidant content using the oxygen radicalabsorbance capacity (ORAC) assay, a widely used and preferredmethod due to its biological relevance to the in vivo antioxidanteffectiveness (Prior and others 2003; Davalos and others 2004).The ORAC method uses the peroxyl radical which is the mostcommon free radical in the human body (Mermelstein 2008). Inshort, as illustrated in Figure 6, the ORAC assay quantifies theantioxidant content by measuring the decrease in fluorescenceover time, and then compares the areas under the curve for thedifferent test substances to a vitamin E analog (Trolox) standardcurve (Prior and others 2003; Davalos and others 2004). ORACassessment of energy drinks in our laboratory resulted in a rangeof antioxidant capacities among the nontea-based beverages of286.3 ± 63.9 to 3393.2 ± 106.1 μM Trolox equivalents (eq.),with an average of 1275.4 μM Trolox eq. The tea-based energydrinks had much higher antioxidant capacities with a range of1749.8 ± 212.7 to 45824.2 ± 1430.6 μM Trolox eq., and anaverage of 10597.9 μM Trolox eq. (Figure 7). The ORAC methodhas limitations and in vivo studies are needed to evaluate if thereare real physiological implications due to the ORAC values de-termined in different energy drinks.

The total polyphenol concentration was measured in the sameenergy drinks with the Folin–Ciocalteu method. This method

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Figure 7 --- A. Comparison showing therelationship of antioxidant capacitywith total polyphenol concentrationfor 16 commercialized energy drinks.B. Comparison showing therelationship of antioxidant capacitywith total polyphenol concentrationfor 15 commercialized tea-basedenergy drinks.

measures the reduction of the Folin–Ciocalteu reagent with thepolyphenols present in the energy drinks and is quantified astotal gallic acid equivalents (Chandra and de Mejia Gonzalez2004). The total polyphenol concentration among the nontea-based beverages ranged from 309.4 ± 1.3 to 1497.5 ± 68.5 μggallic acid eq. with an average of 673.2 μg gallic acid eq. Thetea-based beverages had a range of 496.1± 66.3 to 43010.2 ±18.9 μg gallic acid eq., with an average of 1318.7 μg gallic acideq. Figure 7A shows a comparison of the antioxidant capacityand the total polyphenol concentration in analyzed commer-cially available nontea-based energy drinks. Figure 7B presentsthe results for the tea-based energy drinks. In addition to those en-ergy drinks, yerba mate tea-based beverages were also analyzedfor their antioxidant capacity and their total polyphenol concen-trations (Figure 8). Yerba mate tea-based energy drinks contained100-fold higher amounts of antioxidants and polyphenols com-pared to the mainstream nontea-based energy drinks and the tra-ditional brewed yerba mate tea. Furthermore, the Guayaki yerbamate tea, illustrated in Figure 7B, had the largest antioxidantand polyphenol content among the tea-based drinks suggest-ing the potential of yerba mate as an additive in energy drinkformulations.

According to market research by Mintel, about 60% of the U.S.respondents stated that they look for antioxidants when shoppingfor functional beverages, an area in which energy drink compa-nies capitalize (Lal 2007; Mintel 2007). Increasing the antioxidantand polyphenol contents of energy drinks could be a key driver toincreased sales and can be accomplished by incorporating yerbamate, green tea, ginseng, or fruit juice such as pomegranate andacaı́ into new beverage formulations. A future trend that couldprove to be very effective would be for energy drink companiesto increase the functionality of their beverages to target the grow-ing number of health-conscious consumers (Lal 2007). Areas inwhich these companies could expand could be the inclusion ofvitamin and mineral fortification, organic options, all natural, noartificial flavors, preservatives or natural pigments, weight controlformulations, incorporation of fruits, as well as continuing withthe low carbohydrates and low sugar options that are alreadyhighly visible in the market.

Safety and RegulationsThe regulation of energy drinks varies throughout the world

with the United States having one of the less stringent systems.

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Figure 8 --- Antioxidant capacity andtotal polyphenol concentration is100-fold higher in yerba matetea-based beverages compared tomainstream energy drinks.

The U.S. Food and Drug Administration (FDA 2003) code of fed-eral regulations, nr 21CFR182.1180, lists caffeine, a main com-ponent in energy drinks, as generally recognized as safe (GRAS)when used in cola drinks, at a level of 0.02% caffeine, totaling 71mg for a 12-oz soft drink. This regulation, however, does not ap-ply to energy drinks. In the United States, energy drink companieshave no limitations over the caffeine content of their beveragesbecause the FDA has placed no restrictions on an upper caf-feine limit in these types of beverages. Thus, scientific as well aspublic concern has developed due to the increasing numbers ofenergy drinks entering the market having caffeine concentrationswell above those of mainstream energy drinks, which contain onaverage 10 mg/oz. Energy drink companies must, however, ad-here to labeling regulations for caffeine. Those regulations in theUnited States state that caffeine along with any other ingredientmust be listed on the product label if added to the product as aningredient. However, the actual amount of caffeine, or any otheringredient for that matter, does not need to be listed on the labelleaving consumers uninformed in regard to the amount they areconsuming. Efforts are being done to change this lack of regula-tion as discussed in the 5th amino acid assessment workshop giv-ing priority to developing a safe upper limit for taurine due to itshigh concentration in many energy drinks (Munro and Renwick2006). However, to date there have not been any reported casesof adverse effects due to the consumption of taurine, ginseng, orguarana at levels that are typically found in mainstream energydrinks (Clauson and others 2008). Many countries have addressedthis concern and have developed regulatory guidelines for energydrink manufactures to follow. The Australia New Zealand FoodAuthority (ANZFA) defined a distinct category of beverages called“formulated caffeinated beverages” which must contain no lessthan 145 mg/L and no more than 320 mg/L of caffeine, whichincludes “all caffeine present from whatever source.” The Euro-pean Union has not set an upper limit for caffeine; however, if thebeverage contains more than 150 mg/L, the product label mustread “High Caffeine Content” followed by the amount of caffeine(European Union Commission Directive 2002/67/EC). An initial1st step needs to be taken by the FDA in regard to the regulationof energy drinks, which could be as simple as requiring the man-ufacturer of these products to list the caffeine content as well assupply warnings if their product contains caffeine in the amountof a specified upper level. Increasingly diverse segments of the

population, including children, are choosing to consume energydrinks, which amplifies the importance for the FDA to implementa formal regulatory plan for the production and sales of energydrinks.

PerspectivesEnergy drinks have had exponential growth since their arrival

into the United States and this trend can be expected to con-tinue in the United States as well as abroad. With a society oftime-scarce consumers struggling to maintain a work-life balanceand a younger generation accepting the products market appeal,this growth most likely will continue. The market is becomingflooded with new energy drinks, many with unusual names andclaims of a higher energy boost compared to the previous one,all to get a foot in the door and be noticed. There is, however, aselect few mainstream energy drinks that do control the major-ity of the market and do not have excessive amounts of caffeine,with the majority containing less caffeine than an 8-oz cup of cof-fee. In addition to caffeine, a variety of other active ingredientssuch as taurine, guarana, and B vitamins are incorporated intoenergy drinks to increase some sort of an effect of the product. Be-sides new product launches endorsing their new improved andlonger-lasting energy boost, new developments are anticipatedgeared toward increasing the health functionality of energy drinkswhich will gain market acceptance due to an increasingly health-driven society. However, research needs to continue regardingthe potential benefits of these products to support the claims.The potential health risks associated with heavy consumption ofthese beverages have gone unaddressed and there ought to be agreater need to establish proper regulations. Public concern hasbeen raised regarding the lack of information that is provided onenergy drink labels as well as the high caffeine concentrationsthat are present in some of the more “extreme” energy drinks.To ensure consumer safety, warning labels must be present onenergy drinks that contain elevated levels of their active ingredi-ents, especially caffeine. In addition, an acceptable upper limitmust be put in place for the allowable amount of caffeine thatcan be put in energy drinks just like there is for cola beverages.Enhanced regulations may rid the “extreme,” highly caffeinatedenergy drinks from store shelves and thus protect consumers.

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CRFSFS: Comprehensive Reviews in Food Science and Food Safety

AcknowledgmentThe authors appreciate Dr. Jorge Weil’s comments during the

preparation of the manuscript.

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